This is particularly evident among herbivorous fish, including various tropical perciforms (89). Insect fat body: Energy, metabolism, and regulation. Karasov WH, Meyer MW, Darken BW. Although birds may have a homolog of the lactase gene (162), it is uncertain whether birds are capable of hydrolyzing plant glycosides, which might make them relatively immune to these plant toxins compared to other animals. McWhorter TJ, Caviedes-Vidal E, Karasov WH. In: Lawrence IG, Kostas I, Sarjeet SG, editors. Identification of a variant associated with adult-type hypolactasia. Allometry and ecology of feeding behavior and digestive capacity in herbivores: A review. Adaptive response of equine intestinal Na+/glucose co-transporter (SGLT1) to an increase in dietary soluble carbohydrate. Rossi GD, dos Santos CD, Cardoso MD, Correa AD, de Abreu CMP, Paiva LV. Sklan and colleagues (404406, 445, 446) and Planas and colleagues (16, 413) have studied the molecular basis for ontogenetic changes in carbohydrate digestion and absorption in chickens during the week before and after hatching. Influence of age on lipase, amylase, and protease activities in pancreatic tissue and intestinal contents of young turkeys. Digestive system . This portion of the small intestine involves both the further breakdown of nutrients as well as the beginning of absorption of nutrients. This reduced pH kills bacteria ingested with the feed. Under high glucose conditions, the inward flux of Na+ ions via SGLT1 results in depolarization of the membrane and Ca2+ influx, which, in turn, causes a large-scale reorganization of the cytoskeleton, facilitating access of proteins to the apical membrane. But, another fascinating aspect of lysozymes is that they have been recruited as digestive enzymes over evolutionary time in several vertebrate and invertebrate taxa including foregut fermenting mammals and birds (248), insects (64, 166, 167, 375) and arachnids (Acari) (141). Intestinal nutrient transport during ontogeny of vertebrates. [SGLT1 expression has not been found to be influenced by cdx in mammals (405)]. Chamberlain ME, Phillips JE. Thus, the cecotrophs that reach the stomach contain large amounts of lysozyme and, presumably, of bacteria with partially hydrolyzed cell walls ready to be digested. (A) The dose-corrected plasma concentration of [3H]L-glucose as a function of time since American robins were injected (unfilled symbols) or gavaged (filled symbols) with the probe solution containing L-glucose. Morais S, Lacuisse M, Conceicao LEC, Dinis MT, Ronnestad I. Ontogeny of the digestive capacity of (S. Moran AW, Al-Rammahi MA, Arora DK, Batchelor DJ, Coulter EA, Ionescu C, Bravo D, Shirazi-Beechey SP. The activity of -chymotrypsin and -amylase in the gastrointestinal tract of the locust L. migratoria fed on diets of different composition: PC (21% protein:21% carbohydrate), pc (10.5% protein: 10.5% carbohydrate), Pc (35% protein: 7% carbohydrate), and pC (7% protein: 35% carbohydrate). Identify structures that are a part of the digestive system, respiratory system, circulatory system, reproductive system, and excretory system. Despite the poor capacity of the domestic cat to utilize diets with significant levels of carbohydrate, many commercial cat diets contain relatively high levels of carbohydrate. The peptide transporter family to which the mammalian PEPT1 protein belongs is ancient, with the defining peptide transporter motif (PTR) motif evident in proteins of bacteria, fungi, plants, and animals (107). A dietary supply of cholesterol is not required by mammals, which can synthesize sterols de novo. Absorption of these vitamins is predominantly passive and, unlike other essential nutrients, it is not upregulated in response to low dietary supply (418). Thomas KK, Nation JL. Yoneshige A, Sasaki A, Miyazaki M, Kojirna N, Suzuki A, Matsuda J. Developmental changes in glycolipids and synchronized expression of nutrient transporters in the mouse small intestine. There is a long history of use by humans of natural products as laxatives (31). Levey DJ, Karasov WH. (B) Small intestine nominal (smoothbore tube) surface area in omnivorous birds and mammals (same symbols and lines as in A). The species richness of the microbiota in the GI tract of many invertebrate animals is apparently an order of magnitude lower than in mammals, commonly with just 10 to 20 taxa per individual (7, 22, 123, 131, 285, 381, 475). For example, the elevated expression of intestinal sucrase-isomaltase gene in the intestine of rats and mice fed on high-carbohydrate diets is controlled by the transcription factors Cdx-2 and HNF-1 (36); and the recruitment of these transcription factors to the promoter region is correlated with the acetylation of histones H3 and H4 associated with this gene (215). During the gestational phase, organs undergo morphological maturation [see also reference (354)] and many proteins required for digestion and absorption of components of milk are expressed (e.g., amino acid transporters and the glucose transporter SLGT1). This process occurs very rapidly. Evolutionary design of intestinal nutrient absorption: Enough but not too much. Diet-related determinants of absorption in individual animals are addressed in Section Matches of GI system biochemistry (enzymes, transporters) to changes in diet composition.. The incidence of eukaryotic microorganisms (e.g., protists and yeasts) in the GI tract of invertebrates is not well studied, although the Cryptocercidae woodroaches and lower termites are renowned for their possession of taxonomically unique groups of Oxymonadid and Hypermastigid flagellated protists (91, 349). German DP, Neuberger DT, Callahan MN, Lizardo NR, Evans DH. Ryan CA. This pattern, first described in a survey of more than 40 species drawn from the major vertebrate classes (245), is apparent also in comparative studies within fish (51) and birds (247). They suggested that this is the reason why tubular guts predominate among complex, multicellular animals. Logan JD, Joern A, Wolesensky W. Chemical reactor models of optimal digestion efficiency with constant foraging costs. Caco-2 cells display a third pathway that allows the passage of molecules up to 0.13 nm diameter, suggesting an additional route in the mammalian gut intestine (448). Lysozyme hydrolyzes the bacterial cell walls and the defensins insert into membranes where they interact with one another to form pores that disrupt membrane function and lead to the death of the bacterial cell (268). Barfull A, Garriga C, Montserrat M, Planas JM. A metagenome analysis of fecal samples from 18 human individuals revealed a very diverse array of bacterial genes active against carbohydrates, collectively accounting for 2.6% of the sequences; the particularly high interindividual variation in the complement of glucoside hydrolase genes, even among members of the same family, was attributed to dietary factors (441). Natural toxins are ubiquitous in foods and may influence key features such as digesta transit, enzymatic breakdown, microbial fermentation, and absorption. Digestive Features in House Sparrow Nestlings of Two Ages, and Comparison of Predicted and Observed Changes in Digesta Retention Time and Overall Digestive Efficiency*. Among other passerine birds that do express sucrase-isomaltase, sucrase activity is ten times higher in the hummingbird lineage (Trochilidae), even when compared with other nectar-consuming passerine birds (393). Expression of serine protease Slctlp2 in common cutworm larvae (S. litura; Lepidoptera). The second major phase of changes occurs at the onset of weaning (day 15 in the rat), when the GI tract acquires proteins required for digestion and absorption of solid food that contains substrates not contained in milk, such as fructose and starch. Fractional absorption of the passively absorbed probes declined with increasing molecule size and differed significantly between the two taxa, although the difference diminished with increasing molecule size. Some data suggest that sugar-induced translocation of GLUT2 may not occur universally in mammals (18, 330), and further research is required to establish the distribution of this effect with respect to phylogeny and diet. Juan ME, Turmo MC, Planas JM. Physiological energetics. Timofeeva NM, Egorova VV, Nikitina AA, Dmitrieva JV. Absorption of nutrients in the jejunum and the ileum occurs in the area termed brush border, or the intestinal mucosa (Figure 3). Connor EE, Li RW, Baldwin RL, Li C. Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes. Biochemistry of plant secondary metabolites and their effects in animals. Nevertheless, there is substantial evidence for extensive paracellular transport of solutes in flying birds and fruit bats. Improvements in molecular information have allowed better characterization of the changes in particular genes and proteins responsible for differences in digestive capacity. Thus, IAP helps keep in check the intestines defensive mechanism(s) against bacteria, and in this way, it participates in intestinal tolerance of commensal bacteria. The production of some digestive enzymes appears to be regulated by integrated sensing of both the nutrients available in the gut and the nutritional requirements of the animal. This condition is not, however, universal among insects. The usnic acid-resistant microbe is one of at least three fairly well-documented examples of ruminal microorganisms that can apparently tolerate some SMs. Ventral is the belly side. For example, after urea containing the nitrogen-15 isotope is administered orally to cows, lysine containing that same isotope is found in proteins within tissues of those animals (Fig. van Soest PJ. Free amino acids are taken up from the small intestine of mammals by multiple carriers with overlapping specificities, with the result that most individual amino acids are transported by more than one transporter. In addition, the sodium bicarbonate serves a vital role to provide alkalinity so chyme can be transported though the small intestine without causing cell damage because of the low pH after leaving the stomach. In 1997, Poelstra et al. tract of the human and common laboratory animals can cause significant variation in drug absorption from the oral route. Cloning and characterization of a potassium-coupled amino acid transporter. (248). For example, the magnitude of inhibition of plant cell-wall digestibility was 23% for essential oils, 11% for saponins, and 3% for tannins (all relative to controls). Meissner B, Boll M, Daniel H, Baumeister R. Deletion of the intestinal peptide transporter affects insulin and TOR signaling in Caenorhabditis elegans. Adaptive variation in digestive enzyme activity with diet composition is crucial to the lifestyle of many animals. Knott KK, Barboza PS, Bowyer RT. Daniel H. Molecular and integrative physiology of intestinal peptide transport. . Basic design of vertebrate gut. This role is illustrated vividly by patients with mutations in ABCG5/G8, resulting in elevated absorption and plasma levels of sitosterol, a condition known as sitosterolemia. 10), and the resultant amino acids are exported via transporters on the basolateral membrane (Table 3). At days 6 and 7 of the sixth larval stadium, the larvae stopped feeding and entered the prepupal stage. A number of reviews provide many details of the enzymes structure, pH dependence, function and distribution among vertebrate and invertebrate taxa (88, 246, 419, 428, 429, 457). The density of small tight junction pores varies among cell types and is increased by expression of claudin-2. Exceptionally, amino acid transport in the midgut of larval Lepidoptera is coupled to K+ ions, and not Na+ ions (158, 340). Finally, some GI microorganisms can apparently tolerate high concentrations of tannins, and tannin-tolerant or tannin-degrading bacterial species (189, 388) have been isolated from a variety of wild mammals worldwide, especially those that consume diets high in tannin content (314). Ontogeny of the gastrointestinal tract of marine fish larvae. Food consumption and utilization. How and when selection experiments might actually be useful. Buddington RK, Malo C, Sangild PT, Elnif J. Intestinal transport of monosaccharides and amino acids during postnatal development of mink. 3, top). Jongsma MA, Bolter C. The adaptation of insects to plant protease inhibitors. (A) Maltase activity. food is moved back and forth for mixing . For this reason, pigs have been used in medical research for over 30 years, and are what's known as a translational research model. Evolutionary matches of enzyme and transporter capacities to dietary substrate loads in the intestinal brush border. Harig JM, Ng EK, Dudeja PK, Brasitus TA, Ramaswamy K. Transport of n-butyrate into human colonic luminal membrane vesicles. First, digesta from the small intestine passes into the caecum. A second feature that strengthens the analysis is a larger number of species measured by uniform methodology and subjected to phylogenetically informed statistical analyses. Avian species typically have shorter mean retention time of digesta than do similar sized nonflying mammalian species (315). sharing sensitive information, make sure youre on a federal This means that the pig uterus has two large horns in addition to the body. Hewson-Hughes AK, Hewson-Hughes VL, Miller AT, Hall SR, Simpson SJ, Raubenheimer D. Geometric analysis of macronutrient selection in the adult domestic cat, Hirayama C, Konno K, Wasano N, Nakamura M. Differential effects of sugar-mimic alkaloids in mulberry latex on sugar metabolism and disaccharidases of Eri and domesticated silkworms: Enzymatic adaptation of. Adapted from Figures 1 and and22 from reference (316), with permission. To compensate, they must eat increasing amounts of dry matter, and GI tract size typically increases and/or digesta mean retention time may decrease to accommodate this [Eq. Lysozyme is another antimicrobial enzyme found broadly across vertebrate and invertebrate taxa in many kinds of tissues including the vertebrate intestine. Transcriptional and posttranscriptional adjustments mediate phenotypic changes in the expression of hydrolases and transporters in response to dietary signals. Phenotypic plasticity of gut structure and function during periods of inactivity in. Digestive kinematics of suspension-feeding bivalves: Modeling and measuring particle-processing in the gut of Potamocorbula amurensis. Uptake of di- and tripeptides across the apical membrane of enterocytes is mediated by PEPT1/H+ symport, with the H+ transport coupled to the Na+/H+ antiporter NHE3. In autocatalytic reactions, the maximal rate of reaction occurs at an intermediate, rather than at the highest, reactant concentration. Major changes in GI enzymes and transporters occur during development in many animals. Nevertheless, some studies have found that the secretion of digestive enzymes does not vary in a simple fashion with substrate concentration. Bifano TD, Samuels RI, Alexandre D, Silva CP. The development of the small intestine of piglets - chosen aspects. The digestive system of a pig is well suited for complete concentrate based rations that are typically fed. Shifts during development in feeding versus nonfeeding or in dietary habits occur in diverse invertebrates, including lobsters (235) and insects (301), and digestive enzyme levels may change in correlation with changes in the major dietary substrates. Hrassnigg N, Crailsheim K. Differences in drone and worker physiology in honeybees (. -glucosidase activity has also been measured in guts of numerous invertebrates (5, 143, 151, 157, 183, 374, 391). Twenty a priori predictions about patterns in sucrase, trehalase, maltase, and aminopeptidase N were borne out. Supplies Copies of Handout 1 "Ruminant vs Monogastric Digestive System" make enough copies for group Copies of Handout 2 "Ruminant Digestive System Prehatch intestinal maturation of turkey embryos demonstrated through gene expression patterns. Development of lipase activity in yolk membrane and pancreas of young turkeys. The other midgut trypsin, called early trypsin, is synthesized constitutively. Cant JP, McBride BW, Croom WJ., Jr The regulation of intestinal metabolism and its impact on whole animal energetics. All vertebrates have a small intestine, but vary as to whether they possess other compartments such as crop, forestomach, stomach, cecum, and large intestine/colon. Mining metagenomes for novel cellulase genes. Lipid absorption in insects differs from vertebrates in several important respects. Fischbarg J. Fluid transport across leaky epithelia: Central role of the tight junction and supporting role of aquaporins.
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